1. Carbohydrates

2. Carbohydrates One of the three macronutrients
A primary energy source, especially for neurons (nerve cells)
CH2O
Grains, fruits and vegetables

3. Question
Name ONE other macronutrient & tell me its energy content (kcal/gram)

4. Where do Carbs originate?
As glucose in plants!
Glucose
Most abundant carbohydrate
Produced by plants (& other photosynthetic organisms) via photosynthesis
Simple or complex

5. Data
This is the general equation for photosynthesis—the process of capturing sunlight energy and converting it to chemical energy. Which of the following are the reactants of this reaction?
C6H12O6 and O2.
CO2 and H2O.
Answer: 2

6. Types of Carbohydrates
Simple contain 1 or 2 monomers
Monosaccharides contain 1
Disaccharides contain 2
Complex contain 100’s to 1000’s of monomers
Starches, glycogen, fibers

7. Monosaccharides Glucose: usually occurs with other sugars
Fructose: fruit & vegetable sugar
Galactose: Always occurs with glucose in foods

8. Disaccharides Lactose: Milk sugar (glucose + galactose)
Maltose: Malt sugar (glucose + glucose); by-product of digestion & fermentation in our bodies; substrate for fermentation in beer and liquor)
Sucrose: Naturally occurring fruit sugar

9. Complex Starch: Storage form of glucose in plants
Glycogen: Storage form of glucose in animals
Muscle and liver
Fiber: Form structural support elements of plants

10. What happens to Complex Carbohydrates?
Starch
Digest starch to glucose
Convert it to usable energy, OR
store it as glycogen

11. Complex Carbohydrates
Glycogen
Stored in the liver & muscles
Not a source of dietary carbohydrate

12. Complex Carbohydrates
Fiber
Dietary fiber is the non-digestible part of plants
Grains, rice, seeds, legumes, fruits
Functional fiber is carbohydrate extracted from plants and added to food
Cellulose, guar gum, pectin, psyllium
Total fiber = dietary + functional fiber

13. Digestion of Carbs Begins in the mouth Stops in stomach Resumes in SI
Salivary amylase hydrolyzes starch to short polysaccharides & maltose
What kind of macromolecule is amylase?
Mechanical digestion with teeth
Stops in stomach
HCl denatures amylase
Resumes in SI
Pancreatic amylase also digests carbs to maltose

14. Question
Name another digestive organ that directly adds secretions to the small intestine.
Stomach
Gall Bladder
Liver
a and b
b and c

15. Monosaccharide enter capillaries within the intestinal villi.SI
In the liver, galactose & fructose are converted to glucose.
Figure 4.11: Absorption of Monosaccharides.
Monosaccharides travel to the liver via the bloodstream.
Fig. 4-11, p. 110

16. Transport & Use
ALL monosaccharides are converted to glucose by the liver
Q: Name one other monosaccharide.
Glucose circulating in the blood is our primary energy source
Excess glucose is converted to glycogen by the liver and skeletal muscles
Q: Is this an anabolic or catabolic process

17. Storage of Glycogen

18. Digestion of Carbohydrates
We do not have the enzymes necessary to digest fiber
Bacteria in large intestine can break down some fiber
Produce fatty acids and gas
Most fiber remains undigested and is eliminated with feces

20. Question Where does digestion of Carbohydrates NOT occur? Mouth
Stomach
Small intestine
Large intestine

21. Regulation of Blood Glucose
Amount of glucose (and therefore, access to quick energy) in the blood
Pancreatic cells produce, store and secrete two hormones, insulin and glucagon, which control level of glucose in the blood

22. Regulation of Blood Glucose: Insulin
After eating, pancreas releases:
Insulin
Stimulates cells of the body to absorb glucose from the bloodstream
Stimulates the liver to absorb glucose and convert it to glycogen

23. Regulation of Blood Glucose: Insulin

24. Regulation of Blood Glucose: Glucagon
Stimulates the breakdown (hydrolysis) of glycogen to glucose to make quick energy available to cells of the body
Stimulates gluconeogenesis – production of glucose from amino acids (AA)
Where do these AA come from?

25. Regulation of Blood Glucose: Glucagon

26. Food & Blood Glucose
Glycemic index: A food’s ability to raise blood glucose levels
Foods with a low glycemic index:
Don’t produce dramatic fluctuations in blood glucose
May increase HDL/LDL ratio (good cholesterol)
Are generally higher in fiber
May reduce the risk of heart disease and colon cancer

27. Glycemic indices

28. The Role of Carbohydrates
Energy
4 kcal/kg
Red blood cells rely only on glucose for energy supply
Glucose is especially important for energy during exercise

29. The Role of Carbohydrates

30. The Role of Carbohydrates
Energy
When we do not have sufficient energy in the form of carbs, we produce ketones as an alternate energy source
Why not ketones?
Excessive ketones increase blood acidity
High blood acidity damages body tissues

31. The Role of Carbohydrates
Energy
Insufficient carbohydrate intake forces the body to find an alternate source of glucose
Proteins are used for gluconeogenesis – the production of new glucose

32. Role of Carbohydrates Fiber May reduce the risk of colon cancer
May reduce the risk of heart disease
May block or delay absorption of dietary cholesterol
**May enhance weight loss
Occupies space so you feel full; also absorbs water and expands
**Helps prevent GI diseases/disorders (hemorrhoids, constipation, diverticulosis)

33. How Much Carbohydrate?
Recommended Dietary Allowance (RDA) is 130 grams/day just to supply the brain with glucose
45-65% of daily calorie intake should be in the form of carbohydrates

34. Type of carb matters Most Americans eat too many simple sugars
Most of these come from added sugars
Added sugars = sugars and syrups added to food during processing
Common source is soda pop (~ 10 tsp. sugar per 12 oz. can)
Average American consumes 40 gallons each year!

35. Simple vs. Complex Carbs
Diets high in simple sugars:
Contribute to dental problems such as cavities and gum disease
Cavity causing bacteria thrive on simple sugars
Are associated with increased levels of “bad cholesterol” and decreased levels of “good cholesterol”
These changes are known to cause heart disease

36. Simple vs. Complex Carbs
Complex carbs come associated with fiber
Adequate Intake (AI) of fiber = 14 grams for every 1,000 kcal in the diet
Most Americans eat only 1/2 the recommended amount of fiber
Whole grain foods are a more healthful choice than foods with added sugar
Come stocked with lots of fiber & necessary vitamins and minerals

38. Alternatives to sugar Nutritive sweeteners
Contain 4 kcal energy per gram
Sucrose, fructose, honey, brown sugar, sugar alcohols
Non-nutritive (alternative) sweeteners
Provide little or no energy

39. Alternative Sweeteners
Acceptable Daily Intakes (ADI) have been established for:
aspartame
sucralose
acesulfame-K
No ADI has been set for saccharin but it has been removed from the list of cancer-causing agents.

40. Alternative Sweeteners

41. Health Disorders
Three health disorders related to carbohydrate metabolism
Diabetes
Hypoglycemia
Lactose intolerance

42. Diabetes Diabetes Inability to regulate blood glucose levels
Three types:
Type 1 diabetes
Type 2 diabetes
Gestational diabetes
Untreated diabetes can cause nerve damage, kidney damage, blindness, and death

43. Diabetes Type 1 diabetes Accounts for 10% of all cases
Patients do not produce enough insulin
Causes hyperglycemia – high blood sugar (glucose)
Requires insulin injections
May be an autoimmune disease

44. Diabetes Type 2 diabetes Most diabetics have Type 2 diabetes
Body cells are insensitive or unresponsive to insulin
Excess insulin is often produced
Causes hyperglycemia because cells cannot remove glucose from the blood

45. Diabetes Type 2 diabetes
Causes include genetic predisposition, obesity, and physical inactivity
Treated with diet, exercise, and possibly oral medications
Healthy lifestyle choices may prevent or delay onset of type 2 diabetes

46. Hypoglycemia Hypoglycemia Low blood sugar (glucose)
Reactive hypoglycemia results when too much insulin is produced after a meal
Causes shakiness, sweating, anxiety
Fasting hypoglycemia results when too much insulin is produced even when the patient has not eaten

47. Lactose Intolerance Lactose intolerance
Insufficient lactase production = inability to digest lactose (milk sugar)
Symptoms = intestinal gas, bloating, nausea, cramping, diarrhea
Alternate sources of calcium
Tomato juice, seaweed, cabbage, squashes, beets